This invention relates generally to a device for lifting and positioning building materials and the like. More specifically this invention relates to a lifting and positioning device in which sheets of material such as sheet rock, dry wall or plywood can be lifted and positioned for fastening to ceilings and walls, or subsequently a container of materials such as drywall joint compound for finishing the fastened sheets.
Lifting and positioning sheets of material are important to builders, handymen, and other people who fasten sheets to ceilings and walls. Installers of these sheets are constantly searching for improved methods to lift and position the sheets since the sheets are heavy and awkward to handle. This is especially important when an installer is working alone.
Several prior art lifting devices have been developed which aid in lifting sheets. However, the prior art devices use a relatively large amount of physical exertion to lift the sheet or are expensive to manufacture because they have a relatively large number of piece parts and have built-in, dedicated, actuators such as complicated pulley and rope or cable systems, threaded shafts and hydraulic actuators.
U.S. Pat. No. 4,449,879 issued on May 22, 1984 to James E. Mercer discloses a DRY WALL LIFT that requires a large amount of physical exertion since there are no mechanical or hydraulic multipliers to help lift the sheet. Also, there is no easy method to position the sheet once it is lifted, as the dry wall lift is relatively immobile. The present invention eliminates these shortcomings by providing hydraulic actuation for ease of lifting and transporting elements for mobility.
U.S. Pat. No. 4,175,899 issued on Nov. 27, 1979 to Robert R. Tipton discloses a LIFTING DEVICE that has a relatively large number of piece parts, has a built-in dedicated, hydraulic actuator and also a complicated double parallelogram mechanism for lifting and lowering the platform. The present invention eliminates these shortcomings by reducing the number of piece parts, providing a hydraulic actuator that can be easily removed and used in other applications, and a simple single parallelogram mechanism for lifting and lowering the platform.
U.S. Pat. No. 3,822,023 issued on Jul. 2, 1974 to Ted Cordel discloses a PIVOTING AND LIFTING STRUCTURE FOR SHEETING BUILDING MATERIAL that has a relatively large number of piece parts, has a dedicated threaded shaft for an actuator and also a complicated slide mechanism for raising and lowering the platform. Additionally, the platform is only horizontal at the predetermined maximum height. The present invention eliminates these shortcomings by reducing the number of piece parts, providing a hydraulic actuator that can be easily removed and used in other applications, and a simple single parallelogram mechanism for lifting and lowering the platform, and the platform can be set at any angle between vertical and horizontal and will remain relatively close to that angle during all lifting positions. This is advantageous in that if the platform is set in the horizontal position, it remains relatively horizontal during all lifting heights so the sheets do not fall off.
U.S. Pat. No. 2,789,869 issued on Apr. 23, 1957 to Joel A. Hammagren discloses a HOIST FOR CEILING MATERIAL, which is awkward since both the hoisting rope, and cable actuator must be moved in conjunction with the legs to lift the sheet. Also, there is no easy way to position the sheet once it is raised, as the hoist is relatively immobile. The present invention eliminates these shortcomings by using a simple hydraulic actuator to lift the platform and transporting elements for mobility.
U.S. Pat No. 5,375,963 issued on Dec. 27, 1994 to Clayton E. Wohlwend discloses a MULTIPURPOSE LIFTING APPARATUS which is not designed to lift large flat sheets since it has no platform to accept large sheets and has a dedicated, built-in hydraulic actuator. The present invention eliminates these shortcomings by providing a platform to accept flat sheets and a hydraulic actuator that can be easily removed and used in other applications.